MALIGNANT POTENTIAL OF GASTRIC SUBEPITHELIAL HYPOECHOIC SOLID MASS IMAGED BY ENDOSCOPIC ULTRASONOGRAPHY: A LARGE PROSPECTIVE SINGLE CENTER OBSERVATIONAL STUDY

Aims The malignant potential of gastric subepithelial hypoechoic solid masses (GSHSM) imaged by endoscopic ultrasonography (EUS) is unclear. The aim of this study was to calculate the proportion of malignant tumors in GSHSM using endoscopic ultrasound guided fine needle aspiration (EUS-FNA) results from a large number of patients who have a GSHSM diagnosed by EUS.

Methods From October 2002 to December 2018, 315 consecutive patients with a diagnosis of GSHSM larger than 1cm by standard EUS who underwent EUS-FNA with immunohistochemical analysis were enrolled in this observational study. The technical results and histologic findings of EUS-FNA for GSHSMs were prospectively assessed.

Results The diagnostic rate of EUS-FNA for GSHSM was 86% (270/315). There was no major complication. Histological diagnosis of EUS-FNA, excluding 45 patients with inconclusive diagnosis due to inadequate specimens, showed 72% (195/270) malignant lesions (GIST:69%, SET like cancer: 1%, malignant lymphoma: 1%, metastatic cancer: 1%), and 28% (75/270) benign lesions (leiomyoma: 16%, neurinoma: 5%, ectopic pancreas: 4%, Glomus tumor: 2%, and others: 1%).

Conclusions The malignant potential of GSHSM diagnosed by EUS is high. If we find GSHSM during EUS, performing EUS-FNA is desirable to obtain conclusive immune-histological diagnosis for early appropriate treatment.